The reaction of alkylene oxides, such as ethylene oxide, with alcohols to yield an oxyalkylated alcohol has been known for many years. Commercially, liquid and gaseous sulfonic acids and sulfuric acids have been used as catalysts. The reactors necessary for containing such catalysts are very expensive and in addition, separation of the catalyst from the oxyalkylated product is difficult.
Presumably, sulfonated polymeric substances, such as sulfonated styrene-divinylbenzene polymers or the Amberlyst series of sulfonated polymers (U.S. Pat. No. 3,037,052) would provide a source of sulfonic acid catalytic material that would avoid the problems of the conventional catalysts. However, these catalytic materials have not found wide acceptance in the art because of a number of defects associated with them.
For example, residues from incomplete polymerization, along with initiators for the polymerization, leach out of sulfonated styrene-divinylbenzene resins under any but the mildest reaction conditions. In addition, the sulfonated copolymers in general are fragile, easily crumbled, materials which must be delicately handled. This is a definite drawback when commercial scale operations are involved. A further disadvantage is that the polymers have a low specific activity, so that a relatively large amount of the catalyst must be used.
A final, but very significant, disadvantage of these catalysts is that they cannot be easily regenerated or reused, if the contaminants are not readily removed with warm hydrochloric acid (6N) or its equivalent. Any more-drastic treatment usually degrades the catalyst.